It's great to have you here!
Although selling online is a little different, your retail experience will definitely help you out when you start selling :)
You mentioned that you haven't sold anything online yet: We often recommend that new sellers start by selling items from around the home.
This helps you get to know the process of listing, selling and shipping an item and is very valuable experience before you buy wholesale items for reselling.
You can sell pretty much anything online: Old clothing or jewelry you no longer wear or sporting equipment, DVDs or furniture, so have a look around your home and find a couple of things to list on eBay or another marketplace (Bonanza.com and Addoway.com are great ones to check out!).
You might not make a lot of money on these items, but as I say, the experience gained will really help you out later.
All the best and keep in touch with us!